Borderline personality disorder (BPD) is a sever personality disorder that develops in early adulthood, and is characterized by a lack of control of anger, intense and frequent mood changes, impulsive acts, disturbed interpersonal relationships, and life-threatening behaviors. BPD is relatively prevalent in both clinical and nonclinical populations. Despite the prevalence of this condition, we know very little about how BPD features develop. Although a number of etiological factors have been proposed, studies exploring the etiological relevance of these factors suffer from a number of methodological limitations including: assessing subjects only after they have developed BPD, failing to assess gender effects, and employing cross-sectional designs. This application proposes a two-year prospective multi-cohort study of 500 18 year-old subjects that manifest varying degrees of BPD features; both genders will be equally represented. All subjects will be incoming freshman at the University of Missouri-Columbia, and subjects will complete a number of inventories and interviews at study intake (Time 1) and two-year follow-up (Time 2) that target the following constructs: BPD and other personality disorder features; parental psychopathology; and abuse experiences in childhood. The proposed study has five major aims: (1) to assess the correspondence between alternative measures of BPD features (self-report and interview); (2) to assess the relationship between personality traits and BPD features and determine whether the relations remain significant after partialling out variance in BPD scores accounted for by gender, parental psychopathology childhood physical and sexual abuse, and Axis l pathology; (3) to assess the two-year stability of scores on BPD measures; (4) To evaluate several models of how BPD features develop over time that include personality trail childhood abuse experiences, and parental psychopathology as moderators or mediators; and (5) to assess the relationship between Time 1 BPD symptom scores and negative outcome across a number of domains functioning, and to evaluate the potential moderating influence of personality traits, childhood abuse, and parental psychopathology on the relationship between Time 1 BPD scores and outcome two years later. By addressing these five aims, factors influencing future BPD pathology will be identified, more comprehensive etiological mode for BPD will be empirically evaluated, the level of dysfunction exhibited by syndromal and subsyndromal subjects will be assessed, and the predictive validity of BPD scores will be determined.